TSUMUGU · C1 (est.) · 字
坦
ㄊㄢˇ · tǎn
adj — level, flat; frank, open
字源 FORM — what the parts do
{d,t}ITdàn → tǎn — the {d,t} crossing; tone shifts too
Ground (土) and 旦 dàn carrying the sound, d worn to t. 旦 is the sun flat on the horizon — level all the way out: even ground (平坦), and an open, level heart (坦白、坦然).
故事 STORY — a scene to remember it by
太陽（旦）剛貼上地（土），一片平平展展——坦蕩蕩。
The sun (旦) rests flat on the earth (土), level to the horizon — wide open.
字源記憶法
意 · Meanings
(本義)平坦— level, flat常用
→坦白、坦率— frank, open常用
⇒坦然— calm, untroubled — level inside
(本義) original meaning · → ⇒ each arrow = one more step of extension